DennisAN

As part of my PPS (pre purchase studying) I'm reading about water pump replacement.....

Apparently the factory water pumps had "plastic" impeller blades that would crack loose and lodge in coolant passages, leading to localized overheating. This is a bad thing.

The response here is "only use genuine Porsche water pumps as replacements".

But Pelican lists both the Porsche and Pierburg water pumps as having "composite" impellers. To me "composite" is one form of "plastic". Is this the same faulty design?

Aftermarket suppliers listed at RockAuto include Gates, Bosch, and Beck/Arnley units. As an example the Beck/Arnley states they have a metal impeller. The photo of the Gates unit looks like metal to me too. (I tend to dismiss Bosch water pumps as too many fail over on the Miata forum.)

So how do I square the advice to not use plastic impellers with the advice of only using genuine Porsche water pumps?

LexVan

Buy Porsche water pumps and new gasket for about $310 from places like Sunset and Suncoast. Replace about every 4 years or 60,000 miles.

Don't over-think it.

Just dicsussed last week:

https://rennlist.com/forums/996-foru...-or-metal.html

Macster

I suspect but have no real way of proving this that the faulty design is really just the result of someone letting a pump go too long and the play in the shaft/bearing finally letting the pump impeller blades contact the block. If they contact it with too much force they'll snap. Metal impeller blades will cut away the block material and could run the block.

From what I can gather the standard water pump impeller blades run real close to the block. They have to so the pump is as efficient as it has to be.

That said I'd stick with genuine Porsche original equipment water pumps. The ones I've seen all have a composite plastic impeller which is tough tough plastic. The cam chain rail guides have a plate of this stuff which the chains run against. The intake manifold is made out some composite plastic. The oil filter housing is made out of composite plastic. In fact nearly ever piece of plastic in the engine compartment is made out of composite plastic material. It is as strong as aluminum and lighter.

And last but not least whatever water pump one chooses to run I'd pay attention to it -- though of course not obsess over it -- and at the first signs of any noise or a loss of coolant that should have an inspection of the water pump done. If the inspection finds any signs of coolant leakage at the water pump I'd replace the pump first and ask questions later. To continue to "nurse" a noisy pump or one that is leaking is just asking for trouble.

DennisAN

Part of my question concerns claims from a seller "oh I just changed the water pump 8K miles ago". So basically I really have to grill them about brand of water pump and so forth.

LexVan

Yep. And did they use a new gasket? Did they flush the coolant, too? Did they used distilled water? What about the thermostat? Did they do that, too? And the serpatine belt? All while-your-in-there-stuff.

txhokie4life

The reasoning is that so far in my experience with the water pumps on M96 engines
is "at least with the OEM" you can expect 30K miles.

I have had 2 after markets die within 1000 miles. I have yet to see an OEM that failed with a broken fin.

I had bought a handful of the non-OEM WPs at what I thought was a decent price
-- when the first one died -- I inspected the 2nd one I had installed (both family cars) and
it was already weeping -- I threw it and the other 3 I had in the trash.

All the failures I have seen have been shaft failures (OEM and Non). Either leaking -- or snapping off.

Mike

DennisAN

As I said it's all part of my PPS.

I'm looking for a Boxster project car. My last project car turned out well since the previous owner didn't do much maintenance - which is better than doing a half-assed job on the maintenance. At 140K miles I did the RMS/clutch/timing belt/water pump/brakes/new radiator/9 coolant hoses. I changed all the fluids - even the power steering ATF. It's not rocket science.

I can't believe someone would reuse a gasket, or not use distilled water. I'm so cheap I buy my oil and antifreeze at WalMart but always run my cart past the grocery department and pick up a gallon of distilled water to mix with the antifreeze.

PelicanParts.com

Let us know what you find out there; I suspect there are good choices when it comes to Boxster project cars and it sounds like you have good experience in the DIY dept. Be interesting to see what you buy.
Mark/Pelican Parts

DennisAN

Mark,
I've already bought Wayne's book and the Bentley manual.

See this post for my last three project cars.
https://rennlist.com/forums/11028378-post27.html

The Healey I bought for $300 as a pile of parts. That's Geoff Healey at left in the photo.